keep log_event for compatibility

on import, when enumerating through the 'draft content', OSX environments will have hidden binary encoded quarantine files. We don't want to try to process these as they will throw an exception when trying to be parsed. It's harmless - the import goes on fine - but it's a lot of clutter in the output logs.

STUD-663.

STUD-663

Pylint updates.

Rather than just calling `complex(...)` on the staff answers, also call
`calc.evaluator`. This way, simple things like `1/3` can be entered, as well
as more complicated explicit equations (e.g. `sqrt((12^2 + 26^2)/2)` etc, etc)

Simplify and update the tests to work with this.

and some minor comment changes.

with own db connection.

But don't use this parser for urls embedded in a browser url request. 

unit tests and fixes they implied

partial impl

per our agreement not to use the domain

Fix for video and captions sync. Test for this fix.

xgettext seems to only like `utf-8` not `utf8` so string extraction
was failing without this

And fix get_explicitly_set to use it and to get the json not native
field values.

It's a reasonable demo of in memory xblock creation, but doesn't fit
the xblock pattern. Moving temporarily to keep the dag persistence test.

and fix some comments ref'g old names

Letting xblocks handle scope rather than separating fields into
different attrs. Although, split still shunts content fields to a
different collection than setting and children fields.

The big difference is that content fields will always be a dict and not
sometimes just a string and there's no special casing of 'data' attr.

The other mind change is no more 'metadata' dict.

add a filter to get_courses to not surface any courses that haven't been mapped, unless the store provider has been labeled as 'default'

Because with speed changing the time also changes for Flash playback,
a different way to calculate the current time is needed than for HTML5
playback. I have added conditions for Flash and HTML5 video, and put
old method of calculating time for Flash.

I have tested it on the YouTube video ZwkTiUPN0mg. Both HTML5 mode and
Flash mode have proper video-captions syncing with this fix. NOTE: to view
YouTube video in Flash mode you either have to use an old browser (ex. Firefox
version 18) or hard code in source that state.currentPlayerMode = 'flash' (in
function _setPlayerMode(), file 01_initialize.js).